class Polymorphic:

    def __init__(self, color):
        self.color = color


class Apple(Polymorphic):

    def __init__(self, color):
        Polymorphic.__init__(self,color)
        self.color = color


class Banana(Polymorphic):

    def __init__(self, color):
        Polymorphic.__init__(self, color)
        self.color = color


class FruitShop:

    def sell_fruit(self,fruit):
        if isinstance(fruit,Apple):
            print("sell apple")
        if isinstance(fruit,Banana):
            print("sell Banana")
        if isinstance(fruit, Polymorphic):
            print("sell Polymorphic")


if __name__ == '__main__':
    shop = FruitShop()
    shop.sell_fruit(Apple("red"))
    shop.sell_fruit(Banana("ba"))